The present invention relates to a surgical instrument for displacing bone parts, preferably however an instrument for the expansion of hardened parts.
In particular, the invention is intended for use in surgery on the jaw, to be employed in cases of atrophy, impacted teeth or shrinkage where it is necessary for the purpose of regeneration to separate bone parts and to raise them relative to adjacent bones or to enlarge the distance between the bone part and the bone.
In the known instruments of this type, the bone part is displaced by helical displacement, whereby however elements of the instrument project into the oral cavity of the patient to such a degree that the use of the known instruments is very disturbing to the patient and there is a risk of infection in the mucous membranes and skin exit locations.
The object of the invention is to avoid these disadvantages by an inventive construction of the apparatus.
This object is inventively achieved in accordance with the invention in that an implantable, flat housing is provided in which is located an adjusting device for at least one displacement element, or for two displacement elements that are mutually opposably movable, that can be operated from the exterior via an opening in the housing; the displacement element or elements are longitudinally displaceable bolts that act on counterbearings that are detachably attached to the bones. The bolts are expediently moved by a cone that travels longitudinally with the travel thereof being effected by a toothed wheel or toothed member that can be operated from the exterior and that meshes with a toothed rod attached to the cone.
The housing is preferably attached, for example by being screwed, to the bone or to the bone part to be displaced or raised. However, it is preferable to attach the housing to the actual bone rather than only to a part of the bone.
It is important that the displacement device be encapsulated in a housing that is implantable due to the flat shape of the housing. This arrangement of the instrument beneath the soft tissue ensures that the patient""s discomfort is kept to a minimum. The instrument, in accordance with the invention, is thus patient-friendly and can be used on patients who previously could not tolerate or endure such a surgical procedure.